ELIZABETH — The head custodian at an Elizabeth public school was caught after swiping thousands of dollars in book fair proceeds from the principal’s office, police said today.

Wilfredo Berrios, 52, of Elizabeth, was working at the Nicholas Murray Butler School (P.S. 23) when, on May 31, he went into the principal’s office and took $3,500, police said. The money had been raised at a book fair earlier that month, police said.

Berrios was arrested June 10, police said, after an investigation found surveillance video of the theft, police said.

The school serves students ranging from preschool to 8th grade. The school’s website lists Berthenia Harmon-Carolina as the principal.